This proposal is to fund a Procise Protein Sequencing System. The Model 494 is composed of three integrated molecules: I) the Procise Protein Sequencer, ii) the Model 190-00 Procise PTH System, that includes the Model 140C Microgradient Delivery System and the Model 785A UV Detector, and iii) a Macintosh computer equipped with Procise control software and the Model 610A Data Analysis software. The Procise system will replace an obsolete Applied Biosystems 477A that was purchased in 1987 through a DRR-BRS Shared Instrumentation Grant. The new instrument has been designed to run up to four sample cartridge assemblies independently; thus, the run order, sample type and sequencing method may be customized for each sample. It utilizes multiple types of cartridge assemblies, including the Blot and Micro-cartridge, which are customized for diverse samples: liquid, PVDF blot membranes and micro-quantities. It has the versatility needed to develop new methods for particular samples. A new coupling base, N-methylpiperidine, which is more stable then triethylamine has been substituted in the Edman chemistry. This has effected higher repetitive yields and the ability to perform high- sensitivity sequence analysis. The internal volume from the reaction cartridge to the injection loop has been reduced to less than one-third of the volume in previous models resulting in improved precision and efficiency of the sequence chemistry. For better peak detection and integration, the Procise has a build-in analog to digital converter providing four times the resolution of previous systems. The sensitivity, flexibility and advanced technology of the Procise system is eminently suitable for today's research prerequisites. This instrument would be critical to the needs of a group of highly productive and strongly NIH funded scientists who share a common interest in the misfolding of proteins, with specific focus in amyloid formation and the pathogenesis of Alzheimer's disease.